1. Field Of The Invention
The present invention relates to formed briquettes, processes for forming the same and processes for utilizing the same in steel making.
2. Description Of The Prior Art
Perhaps the most common method of melting iron is through the use of a cupola wherein coke, a fluxing material such as limestone, and a metallic material are charged. The coke is ignited and air is blasted into the bottom of the cupola to generate intense heat, melting the metallic material which then trickles down through the fluxing material and the coke to the bottom of the cupola. A molten slag is formed on the top of the charge and typically comprises coke ash and similar materials.
While the metallic material is typically iron, it would be a great advantage to the industry if metal-containing waste materials as are typically generated in various manufacturing processes could be utilized as a source of metal in such processes. However, to date, the prior art has not provided any means of simply and economically converting metal-containing waste materials into a form which can be used in a process as above described without the use of harmful binders, without relatively low metal proportions which render the same uneconomical or without the generation of fine particles of metal and like materials which are undesirable.
Further, the coke used in most steel-making processes today is high-quality metallurgical grade coke (preferably low sulphur) which is produced by the distillation (in the absence of oxygen) of coal.
After distillation, handling methods in common use break up relatively brittle chunks of coke into a very fine particulate form of coke called "coke breeze." In general, all coke particles that pass through a one-inch mesh size are too fine for use in blast furnace or a cupola melting process.
The reason that coke breeze cannot be used in the steel making industry is that the air blast and intense heat either immediately consume the coke breeze or blow it out of the cupola, with the coke breeze contributing little or nothing to yield heat and potentially creating the danger of explosion. Coke breeze also tends to reduce the necessary freedom of air flow through the melt because it clogs small passageways between chunks of coke.
Attempts have been made in the prior art to form coke breeze into briquettes. However, prior art briquettes have been subject to a number of problems. The most common problem of prior art coke briquettes is that the briquettes have been too brittle to withstand bulk handling and crumble or break into coke breeze.
Attempts have been made to use high proportions of binder to overcome this problem, but when the amount of binder has been increased to an extent that the briquettes are no longer brittle, the amount of binder is so high that it leads to an undesirable amount of slag in the steel-making or iron melting processes and actually can introduce undesirable impurities into the steel, reducing product value.
A further problem of many prior art processes is that high heating conditions are required to form the charge to be briquetted, or high temperature or extended curing times are necessary to form the briquette.
U.S. Pat. No. 4,179,283 Rehder discloses metal oxidecarbon compacts for reduction and combustion in various types of furnaces. Rehder contemplates the mandatory use of two specific types of carbon and does not contemplate the use of metals as is the case per the present invention. Further, the binder systems disclosed in Rehder are totally dissimilar from those of the present invention.
U.S. Pat. No. 3,832,158 Obenchain discloses a process for producing metal from metal oxide pellets in a cupola-type vessel. In a manner similar to Rehder, Obenchain admixes a metal oxide and a carbonaceous material. The only binders disclosed are cementitious materials, which binders are dissimilar from those of the present invention.
U.S. Pat. No. 3,156,557 Dahl et al discloses aggregates of ore, a carbonaceous reducing agent, a flux and a cementitious binder. Dahl et al is cumulative to Rehder and Obenchain and subject to the defects thereof.
Many other processes are also known wherein metal or metal oxides in crude form are processed to final product form, for example, the reduction of chrome concentrates, oxides or ores to ferro-chrome, the reduction of manganese ores to ferro-manganese and the like, and it would be a substantial benefit in such processes if chrome or manganese-containing waste materials could be processed therein.
U.S. Pat. No. 755,278 Kruikshank teaches the manufacture of artificial fuel blocks from anthracite culm, resin dust, asphalt and benzin.
U.S. Pat. No. 756,124 Lieb teaches producing fuel briquettes from a combination of fine coal and resin.
U.S. Pat. No. 1,443,618 Davies discloses a process of making coke which comprises adding substantial proportions of resinous binder to a suitable coal, and then carbonizing the system. A carbonization is required to form the product and very high proportions of binder are present in the finished briquette. The Davies product is also highly perforated to increase the escape of volatile products during carbonization, a procedure not contemplated in the present invention.
U.S. Pat. No. 2,567,136 Vloeberghs discloses fuel agglomerates and a process for manufacturing the same which comprise finely divided anthracite, not less than 6% waste sulfite liquor from the manufacture of cellulose and less than 3% of a synthetic resin such as a phenol-formaldehyde resin. Vloeberghs does not disclose the binder system of the present invention and, due to the presence of the waste sulfite liquor in Vloeberghs, no doubt high amounts of sulfur would be introduced into steel if one contemplated using the Vloebergh agglomerate in a steel-making process.
U.S. Pat. No. 3,402,031 Schick et al discloses an artificial carbonaceous fuel composition particularly adapted for orchard heating. The briquettes comprise a mixture of petroleum coke, wood sawdust, charcoal, an oxidizing agent capable of supporting combustion and a heat-sensitive binder. Useful binders include sugar, molasses, phenolic resins such as phenol-formaldehyde, etc. Other than the use of a resin, which is not the same as that of the present invention, Schick et al differ on almost all points from the present invention.
U.S. Pat. No. 3,836,343 Romey et al discloses carbon-containing briquettes wherein particulate carbonaceous material is mixed with an aqueous suspension of copolymers of butadiene-acrylonitrile.
U.S. Pat. No. 3,843,336 Messman discloses an artificial fireplace log comprising a particulate woody material in combination with a thermoset resin which provides a polymerized casing for the fireplace log. Useful resins include those condensable in thermosetting fashion such as phenol-formaldehyde, resorcinol-formaldehyde or epoxy resins.
None of the references discussed above suggest a briquette exhibiting the unique characteristics of the briquette of the present invention, utilize the binder system of the present invention or suggest utility of the coke-based fuel briquette in steel and/or iron manufacture.
U.S. Pat. Nos. 2,665,977, Engelhart, 4,063,944, Behring, 4,078,902, Olson, and 3,762,886, Triska, disclose fuel briquettes using cement as a binder, certain of these patents disclosing coke breeze being bound by the cement.
Fuel briquettes formed in accordance with this type of prior art is subject to the fault that they exhibit a high ash content and cement is alien to steel-making processes.
U.S. Pat. Nos. 2,508,878, Yates et al., and 2,979,388, Brown et al., disclose the use of organic materials such as asphalt, pitches, thermal tars, and the like, as a binder for a carbonaceous material. The products of these two patents differ substantially from those of the present invention and are subject to the fault that binder materials as are utilized are essentially viscous materials, and they break down during the steel-making or cupola melting process at too early a stage to effectively function in a manner similar to coke.
U.S. Pat. No. 3,676,162, Mehler et al., discloses a basic refractory material for lining steel converters which comprises sintered magnesia bonded with sodium polyphosphate or magnesium sulphate and impregnated with liquid tar. Such a product has a utility opposed to that of the product of the present invention.
U.S. Pat. Nos. 3,879,209 and 4,059,455, both of Limes et al., and 3,960,580, Stierli et al., disclose fastsetting concrete compositions which include magnesia and ammonium polyphosphate.
The following patents generally deal with briquetting finely divided materials: U.S. Pat. Nos. 1,507,674, Nagel, 1,661,636, Simpson, 2,029,309, Curtis et al., 2,711,951, West et al., 3,617,254, Emperato, Jr., 3,674,449, Schmalfeld et al., 3,730,692, Halowaty et al., 3,838,988, Sanada et al., 3,841,849, Beckmann, and 4,015,977, Crawford.
In all of these patents, there is no disclosure of the unique briquette of the present invention nor the properties thereof.
U.S. Pat. Nos. 3,285,758, Limes et al., and 3,413,385, Komac et al., deal with basic refractory compositions and processes for repairing, refractory walls, respectively, wherein a magnesia/ammonium phosphate binder is used.
U.S. Pat. No. 3,708,317, Owen, discloses a metallurgical furnace lining and U.S. Pat. No. 3,826,662, Paolini, discloses a trowelable patching mix for refractory linings containing coke breeze, fire clay and pitch.
U.S. Pat. No. 33,020 Quann discloses a process for reducing iron ore using a solution which includes pulverized charcoa, ammonium carbonate, etc.
U.S. Pat. No. 1,562,564, Kattner discloses briquetting fuels with magnesia cement.
U.S. Pat. No. 2,582,386 Komarck et al discloses a fuel briquette comprising flue dust, clay and an inorganic ammonium compound.
U.S. Pat. No. 4,165,221 Valenti discloses carbon-containing briquettes which are formed from a composition comprising carbon, magnesia and an aqueous ammonium polyphosphate solution. Such introduce harmful phosphorous during steal making.